Glossary
Coolship
A wide, shallow open vessel in which hot wort is left overnight to cool, exposing it to whatever airborne microflora settle in it.
Also called koelschip, kuelschiff.
Originally simply the fastest way to cool wort before heat exchangers existed. In the Pajottenland it survived as the deliberate mechanism of spontaneous fermentation: the wort is inoculated by the ambient microbiota of the brewery and its surroundings.
This is why lambic brewing is seasonal. Summer air carries the wrong organisms in the wrong proportions, so traditional producers brew only in the cooler months.
Related
- Spontaneous fermentation — What a coolship enables.
- Lambic — The style produced this way.
More vocabulary
Beer engine · Foeder · Hydrometer · Kettle · Lauter tun · Mash tun · Refractometer · Sparkler
See every term on the glossary index.
Last reviewed 2026-08-16.